The liquid crystal blue phase is a thermotropic mesophase, usually existing between the isotropic phase and the chiral nomatic phase that was first identified in an 1888 report describing the melting behavior of cholesteryl benzoate. The report noted that the substance briefly turned blue as it changed from clear to cloudy upon cooling. The structure of the liquid crystal blue phase is formed by double-twisted cylinders, which are self-assembled and form three dimensional cubic lattices. Such an arrangement endows the liquid crystal blue phase with special properties, such as optical isotropy, tunable reflection of circular polarized light with certain wavelengths, microsecond response, etc. These properties enable many potential applications of liquid crystal blue phase including high efficiency flat panel displays, fast response optical devices and improved laser techniques. Practical applications using the liquid crystal blue phase have been limited by their stability only in a narrow temperature range (typically about 1 K).
Photoisomerization materials isomerize with irradiation at a certain wavelength, which when present in a liquid crystal, can lead to rotation of the liquid crystals and cause phase transitions. To date, phase transitions of liquid crystals initiated by photoisomerization materials have needed at least 90 seconds, while the recovery time in a dark environment is at least 8 hours.